1. Field of the Invention
The present invention relates to an electric household appliance using a remote controller and, more particularly to an adaptable receiving frequency selection apparatus for the remote controller capable of finding a frequency range having no external electromagnetic wave components and setting the searched frequency range for receiving the remote control signals, and a method therefor.
2. Description of the Prior Art
Recently, most electric household appliances are operated by a remote controller for the sake of a convenience in use. A remote control system includes an independently-constructed transmitting unit, and a receiving unit that is integrally formed with a remote-controlled appliance.
In operation of the remote control system, the transmitting unit encodes with predetermined protocol, remote control signals internally generated in correspondence to any key selected by a user, and then transmits infrared light signals obtained after modulating those encoded signals.
The receiving unit receives the transmitted remote control signals to convert them into the corresponding electrical signals. The converted signal is then demodulated to use in determining which sort of control commands are issued. Subsequently, a control part in the receiving unit controls various parts constituting the appliance so as to operate the appliance in compliance with the finally identified control commands.
For the above-mentioned conventional remote control system, the carrier frequency which falls within around 30-40 kHz frequency range is used in transmitting the control signals, while a ballast for a popular electric fluorescent tube also employs an oscillating frequency falling within a 20-40 kHz frequency range, like that in the remote control system.
Hereby, there is a problem in that the receiving unit may receive undesirable electromagnetic wave components, which can be generated from the fluorescent tube, as normal signals, even if the control signals issued from the transmitting unit are being transmitted towards the receiving unit. The appliance, when it erroneously receives unwanted external electromagnetic wave components instead of a normal control signal, causes a malfunction thereof, or even the system may be halted, which may occur when the unique codes of the appliance become inconsistent with the pre-set codes.